Kathy, Joseph is most likely linked to a family at Closkelt (not far from Banbridge) who were spelling thoer name Megaffin around this time. I have yet to find anyone else doing so. i do not have this person in my records but several Joseph's of earlier generations that I have no descendents for one b 1741 another b 1749. Ohter names in the line are John, James, Richard, Hugh, Samuel, William, Alexander, Mary, Elizabeth, Hanna, Sarah. Do these appear down your Joseph's line?